using 2 different antihistamines whilst on opiates

[dawndoctor]

hey Bl's, sorry if this has been coverd but i couldn't find wat i was looking for..
currently on about 384 mg codeine, 75 ml dxm, 2 mg xanax and 25mg promathezine and was wondering if taking 180mg fexofenadine hcl will help at all with the itching, i don't wanna take more promathezine cause sometimes it just puts me to sleep to easily before i get the most out off the nod... any thoughts or help greatly appreciated

 

[Unknown]

try taking benadryl. I am not familiar with fexofenadine, so I cant help you with that.

 

[blau1005]

Prob a bit late, but fexofenadine is a good choice in this scenario. Quite an effective antihistamine and it's non-drowsy as well. Usually I take promethazine and if it's going to make me too drowsy I'll also use fexofenadine.

 

[lightn!ng]

bumping this thread, I want to do the same thing.

Can someone who knows a bit of pharmacology confirm that if we combine two antagonists (in this case, antihistamines), that their effects will be cumulative, as suggested above? Is there any possibility instead that one antihistamine will in part or in whole block or override the effects of the other antihistamine?

I remember once that I took 15mg mirtazapine and 50mg diphenhydramine. I was surprised that
I did not get the cumulative sedation I would have expected, just the normal level of mirtazapine sedation BUT with some added unpleasant anti-cholingeric effects.

 

[F.U.B.A.R.]

bumping this thread, I want to do the same thing.

Can someone who knows a bit of pharmacology confirm that if we combine two antagonists (in this case, antihistamines), that their effects will be cumulative, as suggested above? Is there any possibility instead that one antihistamine will in part or in whole block or override the effects of the other antihistamine?

I remember once that I took 15mg mirtazapine and 50mg diphenhydramine. I was surprised that
I did not get the cumulative sedation I would have expected, just the normal level of mirtazapine sedation BUT with some added unpleasant anti-cholingeric effects.

Do you mean combining 2 antihistamines with opiates, or just two together? I'm not up on the pharmacology but I can't really see why you'd want to do that in either case. As for mirtazapine, I had a 30mg tablet on top of my usual 60mg of methadone and found it to be not pleasant at all. Yeah it sedated me, but it was a very dirty, unpleasant sedation that put me in a shitty mood for a couple of hours then knocked me out for about 12 hours, then I felt very groggy for the whole of the next day. Anyway, back to the point - I dunno about combining two antihistamines, but I've had good results combing Piriteze (Cetirizine Hydrochloride) and Joyrides (Hyoscine Hydrobromide) with methadone - gives me a right old nod, especially with a few beers

 

[roadkill barbie]

yeah I often take a non-drowsy antihistamine specifically for the itches and a benadryl on top for the potentiating nod factor, no worries - only weird thing is I tend to itch more on ground pods than on DHC and Trams combo,,weird, nevermind

 

[roadkill barbie]

oh shit!! Ive just realised thanks to lightn!ngs above post the anti depressant I'm on , mirtazipine 30mgs is ALSO an antihistamine,, so thats 3 at once,, still having fun though,, I really wouldn't worry

 

[lightn!ng]

Do you mean combining 2 antihistamines with opiates, or just two together? I'm not up on the pharmacology but I can't really see why you'd want to do that in either case. As for mirtazapine, I had a 30mg tablet on top of my usual 60mg of methadone and found it to be not pleasant at all. Yeah it sedated me, but it was a very dirty, unpleasant sedation that put me in a shitty mood for a couple of hours then knocked me out for about 12 hours, then I felt very groggy for the whole of the next day. Anyway, back to the point - I dunno about combining two antihistamines, but I've had good results combing Piriteze (Cetirizine Hydrochloride) and Joyrides (Hyoscine Hydrobromide) with methadone - gives me a right old nod, especially with a few beers

The idea is that the promethazine would reduce itching, and furthermore nausea (through blocking H1 and D2 from the chemoreceptor trigger zone). It would also add some extra sedation.

However, if I'm still itching, I don't want to redose with promethazine because the gross anti-cholinergic effects will become stronger. The addition of a second antihistiamine, in this case fexofenadine, seems to be ideal as it does not cross the BBB and this suggests it will reduce itching without further sedation or anticholinergic effects.

This would done under the assumption however, that the effects of antihistamines are cumulative and do not override or block the effects of other antihistamines in whole or in part when combined. This was not my experience: the time I took mirtazapine and diphenhydramine, I expected to feel the cumulative sedation of both drugs, but instead found that it felt as if the mirtazapine was already occupying diph's sedating 'place', and it was not possible to feel any diphenhydramine-induced sedation while already on mirtazapine. Nevetheless I was able to feel diph's anticholingeric effects. That's why I'm curious about hearing from someone who knows about the actual pharmacology behind it.

Roadkill, what you describe to me sounds like a completely normal first time reaction to mirtazapine. At first, its powerful stuff - Now it barely feels like anything to me.